Abstract: In a lithium ion secondary battery (1), a positive electrode (2) and a negative electrode (3) are alternately adjacent to each other via separators (4) and (5). The positive electrode (2) includes a positive electrode current collector composed of a metal porous body, a first positive electrode active material (21) held on one side of the positive electrode current collector, and a second positive electrode active material (22) held on the other side. The negative electrode (3) includes a negative electrode current collector composed of a metal porous body, a first negative electrode active material (31) held on one side of the negative electrode current collector, and a second negative electrode active material (32) held on the other side. The first positive electrode active material (21) faces the first negative electrode active material (31), and the positive electrode active material (22) faces the second negative electrode active material (32).

Abstract: A power conversion device includes a power converter to output AC power by converting input DC power, an electric leakage detector to detect electric leakage in a power supply line through which the AC power output by the power converter flows when the AC power is being output by the power converter, and a power conversion controller configured to control power conversion of the power converter. The power conversion controller is configured to stop power conversion operation of the power converter based on a detection result of the electric leakage detector.

Abstract: A stator includes piezoelectric vibrators of piezoelectric ceramic put between a long metal block and a short metal block, which are fixed with screw threads at opposite ends of a bolt. When a high frequency alternating current voltage is applied to the piezoelectric vibrators, elliptic compounded vibration, progressive vibration and so on, which is torsional vibration due to the screw threads of the bolt compounded with longitudinal vibration due to the expansion and contraction of the piezoelectric vibrators, is generated on the end surface and the side surface of the stator. A driven member is engaged on the end surface or the side surface of the stator and is driven by the elliptic vibration.

Abstract: In the present invention, a stator consists of a piezoelectric vibrator having divided electrodes on at least one end, alternating current voltage is applied to each of the divided electrodes of one end and one electrode or each of the divided electrodes of the other end of the stator, and a member to be driven is placed on the end or side portion of the stator. The member is reversibly driven by a reversible circumferential progressive wave produced on the end and side portions.

Abstract: Fish sonar signals, temperature signals, PH signals or speed signals of a boat which are emitted from a transmitter as RF signals are respectively received in a wrist watch type receiver, and are displayed on a display device attached to a case of the wrist watch type receiver, whereby each fisherman can see the state of the sea by putting on the wrist watch type receiver to his wrist.

Abstract: A fish sonar buoy is stayed on the surface of the water apart from a boat or shore, ultrasonic signals is emitted from a transmitter-receiver in the water, ultrasonic echo signals in the water are converted to electric signals in the transmitter-receiver, the electric signals are taken in a control circuit during a desired time after ultrasonic signals are emitted from the transmitter-receiver, and thus, a school of fish in the desired position below the water level is detected by a signal information device.